Numerical study of the mixed spin-1 and spin-5/2 BEG model on the Bethe lattice |
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Authors: | R A Yessoufou S Bekhechi F Hontinfinde |
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Institution: | (1) Department of Physics, Erciyes University, 38039 Kayseri, Turkey |
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Abstract: | The mixed spin-1 and spin-
\frac52\frac{5}{2} ferromagnetic Ising model with bilinear (J) and biquadratic (K) nearest-neighbor exchange interactions and a single-ion potential or crystal-field interaction (D) is studied on the Bethe lattice by means of exact recursion equations. First, the phase diagram of the system at zero temperature
is obtained in the (D/Jq, K/Jq) plane, where q denotes the coordination number of the lattice. Second, the sublattice magnetizations
as functions of the temperature, the crystal-field and the biquadratic interaction strengths are thoroughly investigated.
For q = 3, the resulting phase diagrams show first and second order
phase transitions as well as compensation points where the net magnetization of the whole lattice should vanish in the antiferromagnetic
version of the model. One interesting feature of the model concerns the presence of tricritical points. Our calculations show
that at non-zero temperature, none of the sublattice can order separately. However, under an external magnetic field, some
interesting phase diagrams with partially ordered phases arise. |
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Keywords: | |
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